Internal combustion engines are supplied with a mixture of air and fuel for combustion within the engine that generates mechanical power. To maximize the power generated by this combustion process, the engine is often equipped with a turbocharged air induction system.
A turbocharged air induction system includes a turbocharger having a turbine that uses exhaust from the engine to compress air flowing into the engine, thereby forcing more air into a combustion chamber of the engine than a naturally aspirated engine could otherwise draw into the combustion chamber. This increased supply of air allows for increased fuelling, resulting in an increased engine power output.
In conventional turbochargers, engine oil is provided to lubricate and cool bearings in the bearing housing that rotatably support a turbocharger shaft that transfers power from the turbine to the compressor. In addition to cooling and lubrication, the oil provides dampening for shaft and bearing vibrations when provided in thin films as it passes though control or bearing surfaces. Such dampening, which is sometimes referred to as squeeze film dampening, can provide vibration dampening but is often insufficient to provide sufficient dampening in cartridge style bearings. Regardless of its use in the bearing housing, leakage of oil that lubricates, cools or dampens vibrations into a working area of the turbocharger should be avoided during normal operation and also in the event of a turbocharger failure, for example, if a turbine or compressor wheel may be separated from the shaft or fragmented. In the event a compressor or turbine wheel is separated from the shaft neither wheel should exit the turbocharger housings.